1. Field of the Invention
The present invention relates to a printing apparatus, and more particularly, to a printing apparatus in which a main body and a print head replaceable with respect to the main body are electrically connected by a flexible cable.
2. Description of the Related Art
Generally, a printing apparatus drives a print head according to input data and prints text or images on a printing paper. The print head is typically connected to a main body by a flexible cable so as to be reciprocated within a certain range. The flexible cable is formed by printing a signal line on a flexible printing plate, whereby an assembling process is facilitated.
There is high demand for a user's convenience in the maintenance of the printing apparatus. When ink is used up in an inkjet printing apparatus, for example, the print head itself, as well as an ink tank, can be replaced with new ones. Thus, the user can use the printing apparatus without concern for the short life span of the print head.
FIG. 1 shows an existing inkjet printing apparatus as an example of the printing apparatus, and FIG. 2 is a view showing a contact structure for connecting a print head to a printing apparatus.
Referring to FIG. 1, in an inkjet printing apparatus 80, a print head 10 integrally formed with an ink tank is mounted in a carriage 50. The carriage 50 performs a printing operation on a printing paper, while moving left and right along a guide rod 60. Further, a feeding unit 70 supplies the printing paper.
Referring to FIG. 2, a flexible cable 20 and an elastic member 30 are affixed to a fixing portion 40 disposed at the carriage 50 of the printing apparatus 80. If the print head 10 is mounted in the carriage 50, a circuit portion 12 (FIG. 4) of the print head 10 is in contact with an electrical connecting portion 21 of the flexible cable 20. The electrical connecting portion 21 (FIG. 3) of the flexible cable 20 is formed with a plurality of contact points 25 and a circuit pattern 23 corresponding to the circuit portion 12 of the print head 10. FIG. 3 is an enlarged view showing one of the contact points 25 formed in the electrical connecting portion 21 and one of protruding portions 32 for supporting the contact point 25 in the elastic member 30. The contact point 25 of the electrical connecting portion 21 is in the form of an empty dome, and the protruding portion 32 of the elastic member 30 is in the form of a cone. The protruding portion 32 of the elastic member 30 is placed in the hollow dome of the contact point 25 so that the contact point 25 is closely contacted with the circuit portion 12 of the print head 10. To this end, the elastic member 30 is formed of an elastic material such as rubber. FIG. 4 is a view showing the contact point 25 of the electrical connecting portion 21 in close contact with the circuit portion 12 of the print head 10 by the protruding portion 32 of the elastic member 30. As shown in FIG. 4, an apex of the contact point 25 of the electrical connecting portion 21 is point-contacted with the circuit portion 12 of the print head 10 so as to press the circuit portion 12 of the print head 10 by the protruding portion 32 of the elastic member 30. Accordingly, due to the point-contact between the circuit portion 12 of the print head 10 and the apex of the contact point 25, an electric signal of the printing apparatus is transferred to the print head 10, and then the print head 10 ejects ink so as to perform the printing operation.
However, because the contact point 25 of the electrical connecting portion 21 of the flexible cable 20 is point-contacted with the print head 10 in the above contact structure, if the protruding portion 32 of the elastic member 30 does not exactly press a center portion of the contact point 25, the contact is uncertain. Thus, the signal from the main body 80 may not be transferred to the print head 10.
In addition, when the electrical connecting portion 21 of the flexible cable 20 is assembled to the elastic member 30, since the contact point 25 of the electrical connecting portion 21 covers the protruding portion 32 of the elastic member 30, there is a problem that it cannot be easily confirmed whether the protruding portion 32 exactly supports the contact point 25, i.e., whether the protruding portion 32 is apart from the center portion of the contact point 25, as shown in FIG. 5A, due to an erroneous assembling or size of the electrical connecting portion 21, or whether the protruding portion 32 is assembled such that an apex of the protruding portion 32 is bent, as shown in FIG. 5B. If the protruding portion 32 does not exactly press the center portion of the contact point 25, a contacting pressure between the contact point 25 and the print head 10 is lowered; therefore, a contact property of the contact point 25 is degenerated. If the contact property of the contact point 25 is degenerated, product quality is also degenerated.
Therefore, a need exists for a printing apparatus in which a circuit portion of a print head is line-contacted with a contact point of an electrical connecting portion, and a worker in an assembly line can confirm, during the assembling of a protruding portion of an elastic member and the contact point when assembling the printing apparatus, that an apex of the protruding portion can be in close contact with the contact point.